In this
prospective cohort study of pregnant and postpartum women in western Kenya, conducted
between May 2011 and June 2013, more than half of all incident HIV infections diagnosed were acute infections detected during pregnancy. The remaining incident infections were detected shortly after study recruitment and were estimated to have occurred prior to study entry. These findings reinforce
the need for repeat HIV testing during pregnancy and underscore the need to
use more sensitive methods including pooled nucleic acid amplification tests
(NAAT) especially in regions with high HIV prevalence and incidence, Dr Kinuthia
noted.

Women with a
history of sexually transmitted infections (STIs) had close to a four-fold
increased risk of acute HIV infection (OR = 3.8, 95% CI: 1.4-10.6) while being having syphilis or bacterial vaginosis at enrolment had a ten- and close
to three-fold increased risk, respectively (OR = 10, 95% CI: 2.00-46.0 and
OR = 2.6, 95% CI: 1.2-5.8). These findings underscore the importance of screening
for and treatment of STIs in HIV prevention, Dr Kinuthia added.

While much
remains to be done – an estimated 35% of pregnant women in low- and
middle-income countries get an HIV test – considerable progress has been made
in the identification and treatment of women with HIV in prevention of mother-to-child
transmission (PMTCT) programmes.

The
availability of effective antiretroviral treatment for PMTCT and expansion of
ART and access to PMTCT services in many countries in sub-Saharan Africa has
resulted in significant declines in transmission rates. For example, Botswana
and South Africa have reduced transmission rates to below 5%; without any
intervention, transmission rates would range between 25 and 40%.

However, while
women with chronic HIV infection are the primary target of PMTCT programmes, the
need to ensure pregnant women who do not have HIV do not acquire it is of no less
importance in the prevention of adult infection and vertical transmission. Women
in the window period or those who acquire HIV after HIV testing will often go
unrecognised and untreated.

Women with acute
HIV infection have higher viral loads, putting them at increased risk of passing the virus on to their infants, especially if they are not taking
antiretrovirals.

Within this
context, the researchers chose to look at the rates and co-factors linked to
acute HIV infection among pregnant and postpartum women.

Pregnant
women testing HIV negative, following two rapid HIV tests, at their antenatal
visit or within the previous three months were enrolled after consenting. They completed
questionnaires on sexual behaviour and socio-demographic characteristics. Blood
was taken for nucleic acid testing and run in pools of ten samples. Those
who tested negative had tests every 1 to 3 months throughout the nine-month
postpartum follow-up. Genital swabs were collected for STI detection at
baseline and throughout follow-up. Postnatal visits for the most part mirrored
routine immunisation visits.

Of the 4245
women seeking care at Ahero and Bondo district hospitals, where HIV prevalence
at antenatal care clinics is 22 and 26%, respectively, 3408 were
negative and, of the 2351 eligible, 1304 (56%) enrolled in the study.

Women had a
median age of 22 (interquartile range [IQR]: 19 to 26) and 78% (1022) of the women
were married, for a median time of 4 years (IQR: 1 to 8). Seven per cent (87) reported a
history of STIs. One per cent of the women knew their partner was HIV positive while 34%
(445) did not know their partner’s status.

Of these, 10
had a positive NAAT at enrolment (five categorised as seroconversion and five
as acute infection). Fourteen acquired HIV during follow-up; two late in the
pregnancy (week 32), three at 14 weeks postpartum and seven at nine months postpartum.

Of the women
with acute infection, none reported an HIV-positive partner. It is not uncommon
for a man to test by proxy; if a woman tests negative at antenatal care, the partner
assumes he is also negative, said Dr Kinuthia. The partner’s status was not
confirmed. Being married for a shorter period of time (OR = 1.14, 95% CI:
1.01-1.35) was also associated with increased risk for acute HIV infection.

Among women with and without HIV, maternal age, marital status, age difference
from the partner, and infection with other STIs did not differ.

Dr Kinuthia
stressed the need to prioritise strategies to detect and treat STIs. Other HIV
prevention options should be aggressively promoted, he added, including PrEP,
microbicides and promotion of partner HIV testing and treatment.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.